Meteorologist Explains Phenomenon Behind Viral “Firenado” Video

A video showing a spiraling inferno engulfing a British factory before propelling a “firenado” skyward at a height of more than 15 meters (50 feet) has gone viral after the Leicestershire Fire and Rescue Service, Ashby Station posted it to Facebook.

IFLScience spoke with Rob Higham, who was driving when he first spotted the flames and called the fire brigade.

“Whilst waiting for them to arrive I thought it would speed things up if [I broke] the locks off the two large sets of security gates,” said Higham. “I opened up the gates, ready for the arrival of the fire brigade, there were masses of black smoke and huge flames.”

Higham said the factory and yard had 600,000 plastic pallets in it and a few forklift trucks. Around 10 fire engines worked through the night to extinguish the flames. Fire crews offered a simple explanation for how the “firenado” happened on their Facebook post: “It’s created as cool air enters the top of the hot air causing a swirl similar to how a tornado is formed.”

IFLScience spoke with meteorologist Matt Gray, who was not at the scene. He says such an event requires an alignment of perfect conditions.

“Anytime you’re talking about fire, you have an extreme temperature difference between the fire and its surroundings,” said Gray. “The air surrounding the fire heats up and immediately begins to rise, taking the smoke and ash with it. The cool air surrounding the fire will rush in at ground level to take the place of the warm air rising above the fire.”

In simpler terms, a fire whirl is basically the dust devil’s super evil stepbrother. This process is how the fire feeds itself with fresh oxygen, according to Gray.

“If the fire is big enough, it’s really creating its own weather with this process. On the edge of the flames where the superheated air over the fire interacts first with the cooler air rushing in, you can get the flaming vortex that we call a ‘firenado’ or fire whirl.”

Fire whirls don’t occur unless the parent fire’s behavior is extreme, whether that’s with an industrial fire or a wildfire, as was the case earlier this month in Northern California. The intense behavior exhibited by the Carr Fire triggered a fire tornado that has since become the topic of a physics study. In this extreme case, the whirl reached winds of around 230 kilometers per hour (143 miles per hour), or equal to an EF-3 tornado. The event was so extreme that the fire created its own weather pattern. The fire’s column of smoke and ash was so large and hot that it had controlled the path of the blaze, creating local wind and temperature differences.

At the time of publication, the firenado video had been viewed nearly 300,000 times. The factory was destroyed, but thankfully there were no injuries.

A firey tornado rages in Virginia on the Great Dismal Swamp National Wildlife Refuge in 2011. Greg Sanders/USFWS/Wikimedia Commons